Many online services are being inundated by new users that are not people at all, but rather computer programs designed to sign up for thousands of free email accounts, cast votes in online polls, or perform other automated tasks. Since there needs to be some way to tell whether a user is a human or one of these programs, computer scientists at Carnegie Mellon University initiated the CAPTCHA Project. "A CAPTCHA is a program that can generate and grade tests that most humans can pass [and] current computer programs can't pass." The project's homepage lists several areas in which CAPTCHAs are currently being used or have the potential to be used. A couple research papers are available, and visitors to the site can test drive three versions of CAPTCHAs to see how they work.